1. Technical Field
The present invention relates to a multi-walled carbon nanotube impregnated with iron nanoparticles, a method of synthesizing the multi-walled carbon nanotube, and a method in which the multi-walled carbon nanotube is used for the removal of benzene from water.
2. Description of the Related Art
The “background” description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description which may not otherwise qualify as prior art at the time of filing, are neither expressly or impliedly admitted as prior art against the present invention.
Aromatic hydrocarbons (AHs) such as benzene are found in air mainly because of emissions from fuel combustion and vehicle exhausts and other sources. Benzene is a volatile organic compounds and is considered to be a hazardous air pollutant (U.S. Environmental Protection Agency. 2002. “Toxicological Review of Benzene (Noncancer Effects).” http://www.epa.gov/iris/toxreview/0276-tr.pdf—incorporated herein by reference in its entirety). Benzene is a flammable, colorless liquid with a gasoline-like odor (U.S. Centers for Disease Control, (ATSDR). 1997. “Toxicological Profile for Benzene.” http://www.atsdr.cdc.gov/toxprofiles/tp3.html incorporated herein by-reference in its entirety). It is typically used as a solvent and raw material in a broad variety of industrial processes (Wibowo N., L. Setyadhi, D. Wibowo, J. Setiawan, S. Ismadji: Adsorption of benzene and toluene from aqueous solutions onto activated carbon and its acid and heat treated forms: Influence of surface chemistry on adsorption, Journal of Hazardous Materials, 146 (1-2), 237-42 (2007)—incorporated herein by reference in its entirety). Currently, due in large part to vehicle emissions, high concentrations of benzene exist in ambient air and indoor air.
Benzene is found most often in groundwater as a results of leaks in underground pipelines, storage tanks, unintended spills, unsuitable waste disposal practices and leaching from landfills (Shim H., et al., A continuous fibrous-bed bioreactor for BTEX biodegradation by a co-culture Pseudomonas putida and Pseudomonas fluorescens, Advances in Environmental Journal of Research, 7(1), 203-216 (2002)—incorporated herein by reference in its entirety). Benzene may be a cause a lot of health side effects to humans such as leukemia, central nervous system depression, skin and sensory irritation, liver and blood systems, cancer and disturbance of the kidney, reduced weight gain, reducing numbers of blood-forming cells etc. (Murray, F. J., et al. 1979. “Embryotoxicity of inhaled benzene in mice and rabbits.” Am. Ind. Hyg. Assoc. J. 40(11):993-998; Keller, K. A., and C. A. Snyder. 1988. “Mice exposed in utero to 20 ppm benzene exhibit altered numbers of recognizable hematopoietic cells up to seven weeks after exposure.” Fundam. Appl. Toxicol. 10(2):224-232; Keller, K. A., and C. A. Snyder. 1986. “Mice exposed in utero to low concentrations of benzene exhibit enduring changes in their colony forming hematopoietic cells.” Toxicology 42(2-3):171-181—each incorporated herein by reference in its entirety).
The U.S. EPA has set the maximum concentration of benzene at 5 μg/l for drinking water.
There are several processes to treat and remove benzene from water. The adsorption of benzene on carbon nanotubes (CNT) has attracted great interest because of the unique physical and chemical structure properties of CNTs
CNTs showed large adsorption capacity for organic pollutants due to their pore structure and the existence of a wide spectrum of surface functional groups. The adsorption mechanism of benzene on CNTs could attributed to the π-π electron donor-acceptor interaction between the aromatic ring of benzene and toluene and the surface carboxylic groups of CNTs (Lu C., F. Su, S. Hu: Surface modification of carbon nanotubes for enhancing BTEX adsorption from aqueous solutions, Applied Surface Science Journal, 254 (21), 7035-7041 (2008)—incorporated herein by reference in its entirety).
It has been found that CNTs are more effective for the removal of natural organic matter (NOM) than activated carbon (Lu C., F. Su: Adsorption of natural organic matter by carbon nanotubes, Separation and Purification Technology Journal, 58 (1), 113-121 (2007)—incorporated herein by reference in its entirety). Lu et al. used surface modification of carbon nanotubes to enhance benzene and toluene adsorption from aqueous solutions. The NaOCl-oxidized CNTs have superior adsorption performance toward benzene and toluene compared with many types of carbon and silica adsorbents reported in the literature (Lu C., F. Su, S. Hu: Surface modification of carbon nanotubes for enhancing BTEX adsorption from aqueous solutions, Applied Surface Science Journal, 254 (21), 7035-7041 (2008)—incorporated herein by reference in its entirety).
Su et al. employed multi-walled carbon nanotubes (MWCNTs) that were oxidized by sodium hypochlorite (NaOCl) solution to enhance the adsorption of benzene and toluene in an aqueous solutions (Su F., C. Lu, S. Hu: Adsorption of benzene, toluene, ethylbenzene and p-xylene by NaOCl-oxidized carbon nanotubes, Colloids and Surfaces Journal A: Physicochemical and Engineering Aspects, 353 (1), 83-91(2010)—incorporated herein by reference in its entirety).